https_client: trigger connection reset timer on HTTP/2 and send/recv errors, not just timeouts

We saw recurring "curl request failed with 16: Error" (CURLE_HTTP2) and "curl request failed with 55: Error / Send failure: Broken pipe" (CURLE_SEND_ERROR) on a production OpenWrt router running two https-dns-proxy instances, even after tuning max_idle_time down to 30s. These are classic symptoms of curl reusing a stale/half-closed HTTP/2 connection - the same class of problem the existing reset_timer/https_client_reset mechanism was built to recover from, but that mechanism is currently only armed on CURLE_OPERATION_TIMEDOUT. HTTP/2 stream errors and send/recv errors on a reused connection never reach it, so the proxy keeps trying to reuse a bad connection indefinitely instead of forcing a fresh one.

This extends the existing case in https_fetch_ctx_process_response() to also arm the reset timer for CURLE_HTTP2, CURLE_HTTP2_STREAM, CURLE_GOT_NOTHING, and CURLE_SEND_ERROR - all indicators of a broken/stale connection rather than a one-off content error. No new mechanism is introduced; this only widens the set of error codes that trigger the recovery path that already exists.

Tested on a production OpenWrt router (two instances, Cloudflare + Quad9 backends) - confirmed the reset timer now arms and fires (full client reset) in response to these errors, where previously they were silently ignored.

Author: MrObvious

src/https_client.c

@@ -357,6 +357,12 @@ static int https_fetch_ctx_process_response(https_client_t *client,
       WLOG_REQ("curl request failed with write error (probably response content was too large)");
       break;
     case CURLE_OPERATION_TIMEDOUT:
+    case CURLE_HTTP2:
+    case CURLE_HTTP2_STREAM:
+    case CURLE_GOT_NOTHING:
+    case CURLE_SEND_ERROR:
+      // These all indicate a stale/broken (often reused HTTP/2) connection,
+      // not a one-off content error - same recovery path as a timeout.
       if (!ev_is_active(&client->reset_timer)) {
         ILOG_REQ("Client reset timer started");
         ev_timer_start(client->loop, &client->reset_timer);